Biochar is widely used to improve soils, remove contaminants, recycle nutrients, and store carbon. Its quality and long-term stability are often assessed using static chemical indicators, particularly the molar hydrogen-to-organic-carbon ratio, known as H/Corg. Lower values generally indicate a more aromatic and potentially persistent carbon structure.
However, the new article argues that biochars with similar chemical indicators may behave very differently after they are added to soil.
"Biochar is not a single, uniform material," said author Behrouz Gholamahmadi of the University of Aveiro. "Its feedstock, production conditions, interactions with soil microorganisms, and changes during aging can all determine whether it preserves soil carbon, stimulates carbon loss, or provides nutrients. We therefore need to evaluate biochar as a functional material operating within a living soil system."
Biochar made from woody and other lignocellulosic materials commonly contains highly condensed carbon and relatively little easily degradable carbon. These properties may limit microbial stimulation and help preserve native soil organic matter. By contrast, biochar produced from manure, sewage sludge, or nutrient-rich organic residues may contain more nutrients and labile carbon, potentially stimulating microbial activity and accelerating the decomposition of existing soil organic matter.
This process, known as the priming effect, can influence whether biochar delivers a net carbon-storage benefit.
Biochar also changes after application. Surface oxidation, new oxygen-containing functional groups, and changes in pore structure can alter its interactions with water, nutrients, minerals, and microorganisms over months or years.
The article recommends combining conventional indicators with practical measurements such as water-extractable carbon, microbial respiration, short-term soil incubation tests, and basic information about soil conditions.
A performance-oriented framework could help scientists, land managers, certification bodies, and biochar producers select materials for specific goals, including long-term carbon retention, soil fertility improvement, and environmental remediation.
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Journal reference: Gholamahmadi B. 2026. Understanding feedstock-dependent biochar performance beyond static material descriptors. Biochar X 2: e016 doi: 10.48130/bchax-0026-0014
https://www.maxapress.com/article/doi/10.48130/bchax-0026-0014
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About the Journal:
Biochar X (e-ISSN: 3070-1686) is an open access, online-only journal aims to transcend traditional disciplinary boundaries by providing a multidisciplinary platform for the exchange of cutting-edge research in both fundamental and applied aspects of biochar. The journal is dedicated to supporting the global biochar research community by offering an innovative, efficient, and professional outlet for sharing new findings and perspectives. Its core focus lies in the discovery of novel insights and the development of emerging applications in the rapidly growing field of biochar science.
